Professor Knapp has been working for many years in the fields of long-term care, social care, and mental health policy and practice. His current research emphases are primarily dementia, child and adult mental health, autism and long-term social care. Much of his work has an economic focus, and in all of it he seeks to tease out the policy and practice implications. He has published almost 600 peer-review journal papers and 15 books. His work has had numerous impacts on policy and practice in these areas.